/* 清除浏览器默认边距，
使边框和内边距的值包含在元素的width和height内 */

* {
	margin: 0;
	padding: 0;
	box-sizing: border-box;
}

/* 使用flex布局，让内容垂直和水平居中 */

section {
	/* 相对定位 */
	position: relative;
	overflow: hidden;
	display: flex;
	justify-content: center;
	align-items: center;
	min-height: 100vh;
	/* linear-gradient() 函数用于创建一个表示两种或多种颜色线性渐变的图片 */
	background: linear-gradient(to bottom, #f1f4f9, #dff1ff);
}

/* 背景颜色 */

section .color {
	/* 绝对定位 */
	position: absolute;
	/* 使用filter(滤镜) 属性，给图像设置高斯模糊*/
	filter: blur(200px);
}

/* :nth-child(n) 选择器匹配父元素中的第 n 个子元素 */

section .color:nth-child(1) {
	top: -350px;
	width: 600px;
	height: 600px;
	background: #ff359b;
}

section .color:nth-child(2) {
	bottom: -150px;
	left: 100px;
	width: 500px;
	height: 500px;
	background: #fffd87;
}

section .color:nth-child(3) {
	bottom: 50px;
	right: 100px;
	width: 500px;
	height: 500px;
	background: #00d2ff;
}

.box {
	position: relative;
}

/* 背景圆样式 */

.box .circle {
	position: absolute;
	background: rgba(255, 255, 255, 0.1);
	/* backdrop-filter属性为一个元素后面区域添加模糊效果 */
	backdrop-filter: blur(5px);
	box-shadow: 0 25px 45px rgba(0, 0, 0, 0.1);
	border: 1px solid rgba(255, 255, 255, 0.5);
	border-right: 1px solid rgba(255, 255, 255, 0.2);
	border-bottom: 1px solid rgba(255, 255, 255, 0.2);
	border-radius: 50%;
	/* 使用filter(滤镜) 属性，改变颜色。
    hue-rotate(deg)  给图像应用色相旋转 
    calc() 函数用于动态计算长度值 
    var() 函数调用自定义的CSS属性值x*/
	filter: hue-rotate(calc(var(--x) * 70deg));
	/* 调用动画animate，需要10s完成动画，
    linear表示动画从头到尾的速度是相同的，
    infinite指定动画应该循环播放无限次*/
	animation: animate 10s linear infinite;
	/* 动态计算动画延迟几秒播放 */
	animation-delay: calc(var(--x) * -1s);
}

/* 背景圆动画 */

@keyframes animate {
	0%, 100% {
		transform: translateY(-50px);
	}
	50% {
		transform: translateY(50px);
	}
}

.box .circle:nth-child(1) {
	top: -50px;
	right: -60px;
	width: 100px;
	height: 100px;
}

.box .circle:nth-child(2) {
	top: 150px;
	left: -100px;
	width: 120px;
	height: 120px;
	z-index: 2;
}

.box .circle:nth-child(3) {
	bottom: 50px;
	right: -60px;
	width: 80px;
	height: 80px;
	z-index: 2;
}

.box .circle:nth-child(4) {
	bottom: -80px;
	left: 100px;
	width: 60px;
	height: 60px;
}

.box .circle:nth-child(5) {
	top: -80px;
	left: 140px;
	width: 60px;
	height: 60px;
}

/* 登录框样式 */

.container {
	position: relative;
	width: 400px;
	min-height: 400px;
	background: rgba(255, 255, 255, 0.1);
	display: flex;
	justify-content: center;
	align-items: center;
	backdrop-filter: blur(5px);
	box-shadow: 0 25px 45px rgba(0, 0, 0, 0.1);
	border: 1px solid rgba(255, 255, 255, 0.5);
	border-right: 1px solid rgba(255, 255, 255, 0.2);
	border-bottom: 1px solid rgba(255, 255, 255, 0.2);
}

.form {
	position: relative;
	width: 100%;
	height: 100%;
	padding: 50px;
}

/* 登录标题样式 */

.form h2 {
	position: relative;
	color: #fff;
	font-size: 24px;
	font-weight: 600;
	letter-spacing: 5px;
	margin-bottom: 30px;
	cursor: pointer;
}

/* 登录标题的下划线样式 */

.form h2::before {
	content: "";
	position: absolute;
	left: 0;
	bottom: -10px;
	width: 0px;
	height: 3px;
	background: #fff;
	transition: 0.5s;
}

.form h2:hover:before {
	width: 53px;
}

.form .inputBox {
	width: 100%;
	margin-top: 20px;
}

/* 输入框样式 */

.form .inputBox input {
	width: 100%;
	padding: 10px 20px;
	background: rgba(255, 255, 255, 0.2);
	outline: none;
	border: none;
	border-radius: 30px;
	border: 1px solid rgba(255, 255, 255, 0.5);
	border-right: 1px solid rgba(255, 255, 255, 0.2);
	border-bottom: 1px solid rgba(255, 255, 255, 0.2);
	font-size: 16px;
	letter-spacing: 1px;
	color: #fff;
	box-shadow: 0 5px 15px rgba(0, 0, 0, 0.05);
}

.form .inputBox input::placeholder {
	color: #fff;
}

/* 登录按钮样式 */

.form .inputBox input[type="submit"] {
	background: #fff;
	color: #666;
	max-width: 100px;
	margin-bottom: 20px;
	font-weight: 600;
	cursor: pointer;
}

.forget {
	margin-top: 6px;
	color: #fff;
	letter-spacing: 1px;
}

.forget a {
	color: #fff;
	font-weight: 600;
	text-decoration: none;
}